FUMIGATION OF CITRUS TREES. 37 
Having determined this, the dosage strength to use must next be 
learned. On this latter point the writer has spent much time, and 
elsewhere in this bulletin will be found information as to what dosages 
should be used for most of the common scale pests. 
PROCEDURE. 
Five men are required to operate this system to advantage. Two 
men pull the tents and kick in the edges around the bottom of the 
tree. One man takes the measurements of the tree, and should also 
empty the generator to be used for that tree and have it in readiness 
by the time the supply cart arrives. He should empty the generator 
with one and the same hand at all times, and with this hand he should 
never touch the tent. He should also be careful not to slop any of the 
residue on his clothes or shoes lest it be rubbed off on the tent and thus 
produce acid holes. The supply cart, described on pages 22-23, is most 
convenient for carrying the chemicals from tree to tree. Two men 
look after the chemicals — one measures the water and acid, the other 
weighs the cyanid. The latter then holds up the edge of the tent while 
the acid man places the charge beneath the tree. (See PL VIII, 
fig. 2.) 
In actual field practice, after the tent-pullers have commenced 
removing the tents the cart is brought to one end of the row which 
is to be fumigated. (See PL VIII, fig. 1.) The estimator secures 
his measurements and calls them out to the cyanid weigher at the rear 
of the cart, who then determines the dosage from a schedule which is 
fastened to the raised platform. The required amount of chemicals 
is then measured and the tree dosed. While the handlers of cyanid 
and acid are thus engaged the estimator has moved on to the next 
tree, secured his measurements, and holds his generator in readiness 
when the cart is brought up. This tree is dosed in the same manner 
as the first, and thus the procedure continues until the entire row has 
been fumigated. 
The above procedure is such as the writer has used in the field and 
as has been followed by most outfits using the improved system. 
In the procedures adopted by some other outfits there are marked 
differences in the duties of the different men. 
ADVANTAGES UNDER THIS SYSTEM. 
This improved system possesses decided advantages over all 
others. The element of guess in estimating dosage and the conse- 
quent waste of cyanid under the old method are eliminated. With 
the use of a known dosage strength certain definite and uniform 
results occur. The chemicals are measured accurately .and the most 
economical proportion used at all times. Each tree gets the dosage 
scheduled for it — a result which did not always happen under the 
old method, owing to confusion of the cans on the tray. The tent- 
